Machine-switching telephone system.



J. L. McQUARRlE & C. L. GOODRUM. MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED MAR. 30. 1917.

1,252,466.a Patented Jan. 8,1918.

g IIHI- HI-l L g N I H I fnrewfam James L/Vc Quark/e I err/5 Loodrum JAMES L. MOQUARRIE, 0B MONTCLAIR, NEW JERSEY, AND CHARLES L. @OODRUM, 032

NEW YORK, N. Y., ASSIGNOBS T0 WESTERN ELECTRIC COMPANY, INCORPGRATED,

OF NEW YQEK, hi. i, .52. CORPORATIQN OF NEW YORK.

i. MAGHIRFi-KdWETQHIHG TELEPHQNE SYSTEM.

Specification of Letters Patent.

Patented Janfi, 39th..

Application filled hiareh to, 1917. Serial No. 158,566.

The object of the invention is to provide means whereby the capacity of the telephone system may be greatly increased without overtaxing the capacity of the subscribers in manipulating their impulse transmitters.

To increase the capacity of automatic telephone systems utilizing present day apparatus it is necessary to employ a greater number of digits in each telephone designation. This however leads to a psychological difliculty to overcome which a number of schemes have heretofore been devised. The present invention is a scheme which belongs to this class but which has features quite difierent from any other previously devised.

One feature of the present invention is a double dial sending device, each dial containing the regular ten linger holds and arranged upon actuation to send trains of impulses varying from one to ten. Around. the break-points of one dial a resistance is connected, while around the break-points of the other dial there is no circuit.

The choice of the manipulation of one or the other of the dials is determined by the listing of the called line, the characters appearing on the two dials being diiferent.

Another feature is the means for receiving the impulses and differentiating between those of different characters so as to properly control the action of a selector switch. This means consists of two relays, one responsive to weak currents, and the other responsive only to strong currents. The interaction of these relays, under control of the double dial sending device, actuates either one or another of two stepping magnets, one of which is adapted to take only half a step on its first energization, and thereafmr a full step upon each energization, and the other of which is adapted to take a full step upon each energization. I

The manipulation of one dial causes one of these stepping magnets to be actuated, and the manipulation of the other dial causes the other of these magnets to be actuated.

Another feature of this invention is the manner in which the groups of terminals, to which the selector switch is directed, are periodically interspersed between one another. I

The drawing represents a telephone system wherein a calling telephone line and a selector switch embodying the features of this invention are diagrammatically shown, and a line finder switch. a connector switch and a called telephone line are indicated.

DN and DL represent the two dials of the double dial calling device which are shown separately, but which may be combined in a single structure. The mechanical structure of the sending device, however, forms .no part of the present invention. The dial DN operates break-points. which entirely open the subscribers line and the dial DL contains break-points which introduce a resistance B into a subscribers line.

Referring to the diagrammatical representation of the selector switch, LRl/V represents a relay responsive to weal: currents, and LBS represents a relay responsive to strong currents only. These two relays are placed in series, and are controlled by the.

subscribers line until the operations of the selector switch are completed.

Two stepping magnets PMN and PML drive the brushes 13*, B and B in a vertical direction. The first actuation of the magnet PMN is adapted in any well-known manner-such for instance as is disclosed in Patent No. 1,161,837 issued to'Bruce, November 30, 1915-to step the brushes one-half of a full step or a distance equal to the distance between two sets of terminals, such as T, T and T Thereafter, each energization of the magnet PMN drives the brushes a full step or a distance equal to twice thedistance between any two sets of terminals. All energizations of the magnet PML drive the brushes a full step or a distance equal to tvgisce the distance between the sets of termin It is thought that the invention may best be understood through the following detailed descriptionof the operation 1n settin up a connection between a calling and cal ed subscribers lines.

Let it be assumed that the subscriber at the substation S removes his receiver from its hook. The well-known circuits employed in the line finder switch, indicated at LF, cause the connection of the brushes B B and B to the terminals T T T, whereupon the telephone line is extended to the first selector switch FS. A circuit is thereupon established from ground, battery, the windings of relays LRS and LBW, the first position contact and side-switch wiper W, the brush B terminal T the contacts of the dial DN, the apparatus of the subscribers substation S, the contacts of the dial- DL, the terminal T the brush B the sideswitch Wiper W and its first position contact to ground. The relays LRS and LRW attract their armatures, whereby a circuit is established from ground, the armature and alternate contact of relay LRS, the winding of slow release relay SR to battery and ground. The attraction of its armatures by the relay SR prepares circuits for either the magnet PMN or the magnet PML, and, at the same time, opens the release trunk 1, leading to the line finder switch, and the release relay R therein.

In order to illustrate the invention, two actions on the part of the subscriber will be assumed, first, it will be assumed that he manipulates the dial DN to send the selector switch to an odd numbered level of terminals. When this action has been fully described it will be assumed that he manipulates the dial DL, this time to drive the brushes of the first selector to an even numbered level of terminals.

The manipulation of the dial DN, as before stated, entirely opens the subscribers line, and is the well-known action of the present day automatic telephone dial switch. The interruptions in the line circuit cause the vibration of the armatures of both relays LRS and LRW. Upon the first retraction of their armatures, a circuit is established from ground, the armature and normal contact of relay LRS, the armature and normal contact of relay LRW, the outer right-hand armature and alternate contact of relay SR, the side-switch wiper NV. and

its first position contact to a point wherethe circuit divides, extending in one dlrectlon, through the winding of magnet PMN to battery and ground, and in the other direction, through the left-hand winding of rela 2, to battery and ground. As 1n many other well-known systems, the relay 2 1s slow to release, and, therefore, does not respond to the intermittent breakings of its energizing circuits. The magnet PMN,however, does respond to the interruptions, and through the actuation of its armatures, drives the brushes B, B and B to the desired level of terminals.

At the conclusion of this series of impulses the relay 2lslowly deenergizes', due to the attraction of the armatures of the relays LRS and LRW. The energization of relay 2 had established a circuit from ground, contact and armature of relay 2, first position contact and side-switch wlper W, the Winding of magnet E to battery and ground. Upon the retraction of its armature by the relay 2, as just described, relay E becomes deenergized, and in retracting its armature-escapes the side-switch Wipers into their second position.

In the second position of the side switch a circuit is established from ground, the second position contact and side-switch wiper W, the contact and armature of relay SM to battery and ground. Relay SM breaks its own circuit, and, through the consequent vibration of its armature, drives the brushes B*, B and B around and over the terminals T, T and T until an idle trunk is encountered. Such idle trunk is characterized by ground potential on the terminal T and the brush B -upon encountering such a grounded terminal, projects the ground potential over the brush B, through the second position contact and side-switch wiper W through the Winding of the escape magnet E to battery and ground. Escape magnet E thereupon becomes energized and escapes the side-switch wipers into their third position. The seizure of the trunk, throu h the terminals T and T operates in t e well-known manner to remove the ground potential from the terminal T thereby characterizing the trunk as busy.

The connector switch, indicated at CS, is now driven under the control of the dial DN or the dial DL in a manner similar to the actuation of the first selector FS into association with the line leading to the subscribers substation S .The operation of testing and ringing is complete in any wellknown manner, and the connection finally established.

After a period of conversation, the sub scribers hang their receiverson their hooks, whereupon a ground is placed on the terminal T in the manner well known in the art, which ground is thereupon connected through brush B to the third position conthe winding of first selector release magnet Rf to battery and ground, and in the other direction, through the left-hand armature and contact of relay SR, the release trunk 1, the line finder oii-normal contact ON, the winding of line finder release magnet R to battery and ground. Both of these release magnets are energized, and, through their respective armatures and contacts, establish holding circuits which maintain them energized until the line finder and first seleictor switches are fully restored to norma It will now be assumed that the subscriber, instead of manipulating the dial switch DN, manipulates the dial switch DL. The circuit change, which takes place through interruptions of the circuit through dial DL, introduces a resistance R in series with the hue circuit. The current flowing through the line now becomes weak, and relay LRS retracts its armature, but the relay LRW maintains its armature in an attracted position. The interruptions therefore project a ground potential from the armature and normal contact of relay LRS, the armature and alternate contact of relay LRW, the contact and inner right hand armature of relay SR, the side-switch wiper W and its first position contact to a point where the circult divides, extending in one direction, through the winding of magnet PML, to battery and ground, and in the other direction, through right-hand winding of the slow release relay 2, to battery and ground. Slow release relay 2 attracts its armature and thereby energizes the relay E. The actuation of the magnet PML drives brushes B, B and B to the desired even numbered level of terminals. Thereafter, the. action is the same as hasbeen described in connection with the manipulation of the dial DN.

What is claimed is:

1. In a telephone system, means for sending trains of impulses of one character and means for sending trains of impulsespfanother character, selector switches, sets {of terminals therein, means responsive to trains of impulses of one character for setting said switches upon certain of said sets of terminals, and means responsiveto trains of impulses of another character for setting said switches upon certain others of said sets of terminals.

2. In a telephone system, selector switches, fixed terminals therein divided into groups, the terminals of the several groups being periodically interspersed between each other, impulse transmitters arranged to send trains of impulses, of one character, impulse transmitters arranged to send trains of impulses of a different character, means responsive to the impulses of one character for setting said switches on the terminals of one group, and means responsive to the impulses of a different character for setting said switches on the terminals of another group.

3. In a telephone system, directively controlled automatic switching mechanisms, circuits leading therefrom divided into groups, telephone lines, means for causlng said switching mechanisms to extend said telephone lines to one group of said circults,

means for causing said switching mecha-\ nisms to extend said telephone lines to a different group of said circuits, subscriber-controlled means for sending trains of impulses of one character to actuate said first-mentioned means, and subscriber-controlled means for sending trains of impulses of a difi'erent character to actuate said secondmentioned means.

In witness whereof we hereunto subscribe our7names this 27th day of March, A. D. 191

JAMES L. MGQUARR'IE. CHARLES L. GOODRUM. 

